1. Field of the Invention
The present invention generally relates to brake rotors for motor vehicles, including brake rotors which are suitable for race cars.
Further, the present invention also generally relates to brake rotors for motorcycles, including racing motorcycles. Other motor vehicles to which the present invention can relate, include three-wheeled motorcycles, as well as two-wheeled motorcycles, and three-or four-wheeled ATV vehicles.
2. Background Information
In automobile and motorcycle racing, as well as in other contexts relating to motor vehicles, there can be several critical factors which may influence the performance of the vehicle in question. One important factor is weight, in that an excessively heavy vehicle may not be able to perform effectively. This factor may, for example, have a decisive influence on the speed and fuel economy of the vehicle. Another important factor may be the ability for the vehicle to brake effectively. Particularly, the ability of the vehicle to stop quickly and efficiently, as well as the need to prevent excessive overheating of the brakes, can be tremendously important.
Conventionally, brake rotors have been formed of cast iron or steel, and often do not have a coating for serving as a thermal barrier.
A disadvantage often encountered with such rotors is excessive weight, both in terms of unsprung weight and rotating weight. Such excessive weight may often result in poor fuel economy, as well as an inhibited capability to accelerate. Typically, such a rotor may weigh approximately fifteen pounds, which would typically result in a total weight, for four brake rotors un a four-wheeled vehicle, of about sixty pounds. This has long been considered to be excessive for certain contexts, particularly for the context of race cars.
In conventional rotors, braking problems may also result from a coefficient of friction which may not be as high as desired for certain applications, such as in the context of race cars or racing motorcycles. In the case of conventional cast iron rotors, another disadvantage often encountered is the presence of void or stresses in the casting.
It has been known that the weight of conventional rotors can be reduced by utilizing a lighter material, such as aluminum. If, for example, a lightweight rotor, which may include aluminum, is provided on a vehicle, such as a race car or racing motorcycle, the unsprung weight and rotating weight of the vehicle may be reduced by as much as forty-eight pounds, particularly if each rotor weighs only about three or four pounds.
It has also been known to coat the braking surfaces of a brake rotor with ceramic, in order to provide a higher coefficient of friction than would normally be encountered with a plain cast iron or steel rotor. To date, such ceramics have often included a variety of materials. However, problems relating to durability may be experienced in these contexts. Particularly, in many known applications, it has been found that the ceramic coating may have a tendency to develop cracks with increased use, especially if high braking temperatures are created at the surface of the ceramic coating.
U.S. Pat. No. 5,224,572 discloses the provision of a ceramic coating on each of the two braking surfaces of an aluminum rotor. As disclosed therein, a plurality of circumferentially spaced cooling apertures are arranged between the braking surfaces. The apertures extend radially, between the large central aperture of the rotor and the outer circumference of the rotor, and essentially act to vent away excessive heat. However, it has been found that this aluminum vaned rotor is not necessarily provided with as significant a degree of thermal protection as may often be desired in certain contexts, such as in the context of a racing car or racing motorcycle. Further, it has been also found that this aluminum vaned rotor does not necessarily provide as great a reduction in either unsprung weight or rotating weight as may otherwise be desired in certain contexts, such as in the context of a racing car or a racing motorcycle.
In the context of motorcycles, including racing motorcycles, it would appear that weight reduction can be a particularly important consideration. Particularly, for a given rotor, it would appear that a reduction in rotor weight would be proportionally more significant in a motorcycle than in an automobile, owing to what would appear to be a significantly proportionally reduced weight of a motorcycle in comparison with an automobile. Thus, it would appear that a motorcycle, such as a racing motorcycle, having rotors with significantly reduced weight in comparison with conventional rotors, could be at a tremendous advantage with regard to performance and fuel efficiency, especially in the context of racing.
To date, another type of known rotor in wide use has been the carbon-fiber rotor. When initially manufactured, carbon-fiber rotors appeared to possess significant advantages over prior known rotors, especially in the context of motorcycles and racing motorcycles.
However, it is now believed that carbon-fiber rotors have fallen out of favor among, and have even been prohibited by, certain racing organizations. Further, carbon-fiber rotors can tend to be expensive to manufacture, and may not necessarily provide the desired advantages of heat resistance.
This inventor tried bare rotors made of a titanium composition. However, bare rotors having a titanium composition did not always tend to provide desired advantages of heat resistance or reflection. Further, at high speeds and high brake temperatures, bare titanium rotors, as well as other bare rotors, may "gauld" or "gall". Such "gaulding" or "galling" can essentially be thought of as undesirable rubbing or chaffing on the rotor surface, with the result of wearing away part of the rotor surface, at least partly possibly accounted for by the swelling of the rotor surface at high temperatures.
Therefore, it appears that a need has arisen for lightweight rotors capable of enhancing the performance and fuel efficiency of motor vehicles, including motorcycles, and which do not possess the disadvantages either of carbon-fiber rotors or of other rotors, such as bare titanium rotors.